JP4621373B2 - Apparatus for shielding an apparatus from a semiconductor wafer processing chamber - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a semiconductor wafer processing chamber, and more particularly to a heat shield for shielding a device such as a pump from thermal energy generated in the semiconductor wafer processing chamber.
[0002]
[Prior art]
The first and second stages are pumped down to create a sufficient vacuum to process the semiconductor wafer in the processing chamber of the semiconductor processing system. In general, in the first stage, the chamber is evacuated and directed to a first vacuum level. Most of the air is removed from the chamber, a vacuum is established, and the second stage begins. During the second stage, a cryogenic pump (usually called a cryopump) is used to achieve a high vacuum level in the processing chamber. A system that uses a cryopump and achieves high vacuum is a physical vapor deposition (PVD) system that requires base pressure (ie, sputtering gas without intent to fill) on the order of 10 ^-9 torr. To obtain optimal processing conditions and processing performance.
[0003]
Generally, the cryopump generates a high degree of vacuum in the chamber by removing molecules and other gases remaining in the chamber atmosphere after the first stage pump down. Generally, a cryopump has a plurality of blade arrays. Each blade of each array is fabricated from a material that absorbs molecules and other gases that come into contact with the blade during the pumping process at low temperatures. Only a finite number of molecules can be absorbed by the cryopump, making the capacitive pump sensitive to loading from sources other than the chamber atmosphere. At the processing point, preferably after a significant number of wafers have been processed in a vacuum atmosphere, the cryopump is heated to exhaust, ie, absorb or exhaust, molecules and other gases absorbed and collected during pumping. As generally stated, the cryopump absorbs gas as it cools, and then gradually increases its ability to absorb gas as the temperature of the cryopump increases until it reaches the temperature at which the cryopump absorbs gas. To lose. As such, the temperature of the pump directly affects the ability of the cryopump to achieve and maintain a high vacuum (the cryopump must remain cool to effectively achieve the high vacuum).
[0004]
Usually, the cryopump is connected to the inlet / outlet of the processing chamber via an elbow tube. The elbow tube functions to protect the cryopump from the heat generated in the chamber by lamps, pedestal heaters, plasma and other heat sources in the chamber. The elbow tube insulates the cryopump by placing the cryopump at a certain distance from the chamber where the heating effect from the chamber is not so severe. Furthermore, the elbow shape of the tube places the cryopump outside the direct range of radiant energy exiting the chamber through the inlet and outlet. The doorway is also typically attached to a shield and reflects the radiant energy generated in the processing chamber.
[0005]
Before the processing chamber is used to process semiconductor wafers, the chamber experiences a process known as “baking out”, the chamber is heated by a lamp and absorbs volatile molecules from the surface exposed to the interior of the chamber. Evaporated. Removal of these molecules is important to achieve high vacuum and to minimize contamination of the substrate processed in the chamber.
[0006]
Once volatile molecules are pumped out of the chamber, the chamber is cooled to a nominal temperature over a period of time known as the cooling period. After both the bake out and cool down cycles are complete, the chamber is eligible to process wafers when the chamber can achieve and maintain a vacuum degree on the order of 8 × 10 ⁻⁹ to 5 × 10 ⁻⁹ Torr. It is thought that there is.
[0007]
[Problems to be solved by the invention]
Several problems have been observed in systems that use cryopumps that contribute to the difficulty of achieving and maintaining high vacuum. One problem is the difficulty of absorbing volatile materials and other contaminants from the elbow tube. The position of the elbow tube between the chamber and the cryopump prevents the heating of the elbow surface required to remove contaminants from the elbow surface during bakeout. As a result, the elbow tube may degas the material that loads the cryopump before high vacuum is achieved, i.e. when the chamber surface degassing reaches a fairly low rate, You may continue to deaerate. Still further, the curved profile of the elbow tube causes molecules and other contaminants to impact the interior of the elbow tube as it exits the chamber through the doorway. These molecules and contaminants are later removed, preventing the cryopump from reaching the desired vacuum level, or drifting the vacuum pressure due to cryopump molecular loading from the evacuated elbow material.
[0008]
Another problem is that the heat shield is typically made of aluminum. The aluminum heat shield quickly becomes hot and eventually becomes a heat source for the cryopump because the shield is close to the pump. The fluid path in the aluminum shield, or the shield mounting flange for cooling, is disliked because the fluid path placed in the vacuum atmosphere can be catastrophic chamber contamination when fluid leaks.
[0009]
These problems integrate and contribute to a long limit on the number of chamber bakeouts, limiting the performance of the cryopump and reaching and maintaining high vacuum levels. This reduces tool performance and consequently reduces manufacturing throughput and manufacturing costs.
[0010]
Therefore, there is a need in the art for a heat shield that improves the performance of the cryopump by shielding the pump from thermal energy generated in the semiconductor wafer processing chamber.
[0011]
[Means for Solving the Problems]
The disadvantages associated with the prior art are overcome by the apparatus of the present invention located at the inlet of an apparatus such as a cryopump, which shields the cryopump from the processing chamber of the semiconductor wafer processing system. In particular, the device includes a shield member coupled to the mounting flange. The mounting flange includes a fluid path located outside the seal area so that failure of the seal does not contaminate the processing chamber.
The fluid path is adapted to flow fluid and transfers heat between the shield members.
[0012]
In one aspect of the present invention, the inventive apparatus reflects thermal energy generated in the processing chamber and transfers thermal energy absorbed by the heat shield to the heat transfer fluid. Therefore, the shield of the present invention can maintain the inside of the chamber at a high vacuum by attaching the cryopump near the chamber and increasing the efficiency of the cryopump.
[0013]
DETAILED DESCRIPTION OF THE INVENTION
The teachings of the present invention can be readily understood by considering the following detailed description in conjunction with the accompanying drawings, in which:
[0014]
For ease of understanding, identical reference numerals have been used, where possible, to designate identical elements that are common to the drawings.
[0015]
FIG. 1 is a simplified schematic diagram illustrating a heat shield body 118 of the present invention incorporated into a semiconductor wafer processing system 100. The present invention effectively shields equipment from thermal energy generated within the processing chamber 116 of the semiconductor processing system 100. The present invention is generally applicable to vacuum chambers in semiconductor wafer processing systems, for example, physical vapor deposition chambers (PVD) or sputtering chambers, chemical vapor deposition chambers (CVD), and device heat shields are desired. High temperature chamber (HTC) and other chambers.
[0016]
As an example, FIG. 1 schematically illustrates a PVD or sputtering system 100. The system 100 includes a cryogenic pump (cryopump) 190, a rough pump body 140, a processing chamber 116, a heat shield body 118, and a fluid source 176.
[0017]
The exemplary processing chamber 106 includes a chamber wall 114 and a target plate 116. A target plate 106 is disposed on top of the chamber wall 114 and surrounds the processing chamber 116. The plate 106 is electrically insulated from the chamber wall by an annular insulator (not shown). In general, O-rings (not shown) are used above and below the insulator to provide a vacuum seal to ensure a complete vacuum in the chamber 116. The target plate 106 may be made of a material that will be a deposition material, or may include a coating of the deposition material. A high voltage DC power source 102 is connected between the target 106 and the chamber wall 114 to facilitate the sputtering process.
[0018]
Chamber wall 114 and target 106 define a chamber volume 117. The chamber wall 114 further includes a first entrance 108 and a second entrance 111. The first entrance 108 is smoothly connected to the rough pump body 140. The rough pump body 140 normally includes a shut-off valve 144 and a rough pump 142. The shutoff valve 144 is coupled between the rough pump 142 and the first inlet / outlet 108. When the shut-off valve 144 is activated and, for example, a first level of vacuum is reached in the chamber 116, the rough pump is isolated from the chamber volume 117.
[0019]
The second inlet / outlet port 111 is arranged in a chamber capacity that allows fluid communication with the cryopump 190. The shutoff valve 185 is coupled between the second inlet / outlet port 111 and the cryopump 190. Shutoff valve 185 insulates cryopump 190 when the pump is not in use.
[0020]
The stage 135 is disposed in the chamber 116 and holds and supports the substrate 120. The table 135 may be heated, but is moved up and down by an elevator system (not shown) to place the substrate 120 with respect to the target plate 106.
[0021]
The shield body 118 is disposed near the second entrance / exit of the processing chamber 116 and shields the cryopump 190. Alternatively, the shield body may be used to shield other temperature sensitive devices such as probes, sensors and the like. The shield body 118 includes a mounting portion 202 coupled to a heat shield 206 by a support member 204. The mounting portion 202 is connected to the chamber wall 114 and the heat shield is disposed in the chamber volume 117.
[0022]
FIG. 2 is an exploded perspective view of the shield body 118. The mounting portion 202, shown as a mounting flange in the first embodiment, is typically made of a heat conducting material, such as copper. In general, in the preferred embodiment, the attachment portion 202 comprises a generally annular ring, such that the ring has the same circumferential profile as the chamber opening attached to the first surface 210 and the opposing second surface. It is configured. The plurality of mounting holes 208 pass through the mounting portions 202 evenly spaced around the bolt. The grooves 216 are supplied radially inside the mounting hole 208 on both the inner and outer surfaces. A groove 216 in each such surface 210, 212 is provided to receive the seal ring 217. The seal ring 217 has a seal surface 214 and is generally exposed on the same plane as the surfaces 210, 210 of the mounting portion 202. The knife edge 216 extends outwardly from the sealing surface 214 around the exposed periphery of the seal ring 217. The seal ring 217 is made of a material such as stainless steel. In general, the material of the seal ring 217 is selected to be harder than the gasket material (306 and 308, see FIG. 3) used between the shield body 118 and nearby components to ensure reliable airtightness. The shield body 118 is reused after being removed from the processing chamber 116. Preferably, the seal ring 217 is affixed within the groove 215 by vacuum brazing, although other stringent sealing methods such as adhesives and interference fits may be used instead.
[0023]
A flow path 220 is disposed radially outward from the mounting hole 208 and within the mounting portion 202, and is therefore positioned completely radially outward from the position of the seal ring 217. The flow path 220 is substantially circumscribed by the mounting portion 202, starts at the inlet 222, extends around the bolt and into the periphery of the mounting portion 202, and ends at the outlet 224. Inlet 222 and outlet 224 are preferably threaded in NPT or other thread form and receive a commercial fluid connector (not shown) therein. The flow path is coupled to a fluid source 176 (shown in FIG. 1) through an inlet 222 and an outlet 224 from which fluid is supplied and flows through the flow path 220. The fluid extracts the heat conducted to the fluid through the attachment portion 202 (or instead introduces heat, depending on whether heating or cooling of the shield 118 is desired), thereby causing the temperature of the shield 118 to increase. Adjust. As the fluid circulates from the fluid source 176 through the mounting portion 202, the amount of heat removed from the shield body 118 is controlled by changing the fluid, flow rate or fluid inlet temperature, thus causing the shield body 118 to move to a predetermined temperature. To maintain.
[0024]
The fluid may be a liquid and / or gaseous fluid, but in one embodiment is a liquid such as deionized water and / or ethylene glycol. Other fluids such as liquid or gaseous nitrogen or freon can also be used.
[0025]
In one embodiment, the flow path 220 is fabricated by forming a conduit 226 on the second surface 212 of the mounting portion 202. The plug 228 is then attached to a conduit 226 that is flush with the second surface 212 to form the flow path 220. The plug 228 is affixed to the conduit 226 in a manner that prevents leakage of fluid flowing through the flow path 220 using, for example, interference fit, adhesive, welding, brazing, and other methods of connecting these parts. Is done.
[0026]
The support member 204 is generally made of a material having good thermal conductivity, for example, copper. The support member 204 supports the heat shield 206 while minimizing the protruding region that blocks the gas flow path passing through the second inlet / outlet 111. The support member 204 includes a cross member 230, a support rod 234, and a mounting block 232. The cross member 230 is coupled to the attachment portion 202 at its end and preferably extends in a straight line with the diameter of the generally annular attachment portion 202. The support rod 234 extends perpendicularly from the cross member 230, preferably midway between the ends of the cross member 230 and ends at the mounting block 232.
[0027]
In general, the support block 232 is rectangular in shape and includes a groove 236 disposed opposite the connection of the mounting block 232 to the support rod 234. The mounting block 232 further has a plurality of holes that pass through the mounting block 232 orthogonal to the groove 236 and are spaced around the groove 236.
[0028]
Generally, the heat shield 206 is a good heat conductor, eg, copper. The heat shield 206 has a heat reflective finish. In one embodiment, the heat shield is finished with a metal plating such as nickel, gold, silver or other heat reflecting material. In all cases, the reflective finish must be chosen so that the emissivity is low at the operating temperature and wavelength. The shield member 240 has a concentric curved shape at the peripheral edge of the table 135 and reflects heat away from the cryopump 190 (as seen in FIG. 1).
[0029]
The attachment pad 242 is disposed at the center of the shield member 240. The mounting member 242 includes a tab 244 protruding outward. The tab includes a plurality of holes 246. Tab 244 fits into groove 236 such that holes 238 and 246 are aligned. A fastener, such as a presser screw 248, is inserted through the holes 238 and 246 and into the through hole 252 of the mounting plate 250, thereby fixing the heat shield 206 to the shield body 118. In this manner, the coupling between the mounting pad 242 and the groove 236 of the mounting block 232 allows heat to be transferred and effectively occurs between the heat shield 206 and the support member 204.
[0030]
FIG. 3 shows an exploded view of the chamber body, valves and pump, including a cryopump 190, a shutoff valve 185, and a shield 118 to the second inlet / outlet 111 of the processing chamber 116. For the best understanding of the present invention, readers are encouraged to refer to FIGS. 2 and 3 simultaneously.
[0031]
Proceeding from the processing chamber 116 to the cryopump 190, the processing chamber 116 has a flange 302 that circumscribes the second inlet / outlet port 111. The flange 302 includes a plurality of through holes 304 attached around the same bolt around the bolts 208 of the attachment portion 202. The through studs 310 are partially disposed in the respective through holes 304, and most of the studs 310 protrude outward from the flange 302. For clarity, only one of the through studs 310 is shown in FIG. Shut-off valve 185 and cryopump 190 also have a plurality of holes 208 that are identical to those found in mounting portion 202.
The mounting portion 202, the shut-off valve 185, and the cryopump 190 are disposed in the through stud 310, and the through stud 310 passes through the mounting holes 208 of the respective components.
[0032]
First, a deformable gasket 306 having minimal temperature characteristics and high temperature conditions under vacuum is disposed between the mounting portion 202 and the flange 302. The second gasket 308 is similarly disposed between the mounting portion 202 and the shutoff valve 185. The first gasket 306 is compressed between the sealing surface of the seal ring 217 and the knife edge 216 and the flange 302, and the second gasket 308 is tightened with the nut 312 to the stud 310, thereby Compressed during edge 216. A stop washer 314 is disposed between the nut 312 and the cryopump 190 to prevent the nut 312 from loosening. When the gaskets 306 and 308 are compressed, the knife edge 216 of the sealing surface 214 is in point contact with the respective gasket, thus ensuring a seal between the components.
[0033]
Referring primarily to FIGS. 1 and 3, in operation, substrate processing begins by placing a substrate on a pedestal 135. The processing chamber 116 is evacuated using a rough pump body 140. A large amount of gas in the chamber volume 117 is removed by the rough pump 142 and a first vacuum level is obtained in the processing chamber 116. Thereafter, the shutoff valve 144 is started to insulate the chamber capacity 117 from the rough pump 142. Once the first vacuum level is obtained, shutoff valve 185 is opened and cryopump 190 is started to further increase the vacuum level.
[0034]
What is the thermal energy during the pump down process and the next substrate processing? Generated from an array of sources including lamps, plasma, pedestal heaters and other heat sources. A part of this heat is radiated to the shield member 206. The reflective finish of the shield member 206 reflects a portion of this thermal energy, returns to the processing chamber 116, and leaves the cryopump 190. The thermal energy absorbed by the shield member 206 includes a portion of the radiant energy that is not reflected and is conducted from the shield member 206 through the support member 204 to the mounting portion 202. Thereafter, thermal energy is transferred from the fluid source 176 and thus from the attachment portion 202 to the fluid circulating through the flow path 220 of the attachment portion 202. As such, the heat shield body 118 provides thermal regulation and substantially protects, ie shields, the cryopump 1902 from the effects of heat from the processing chamber. Accordingly, the cryopump 190 is sufficiently cooled to reach a vacuum level exceeding 10 ⁻⁹ Torr.
[0035]
The exhaust area requires heating, after which the heated fluid passes through the shield. Thermal energy is transferred from the fluid to the mounting portion 202 and through the support member 204 to the shield member 220. Heating the shield body 118 may assist in heating the cryopump 190 during the pump discharge cycle. In addition, heating of the shield 118 protects the outlet area from reaction by-products by contaminating the deposition material or minimizing condensation at the proximity surface. Minimizing contaminant deposition in the outlet area extends the service life of probes, sensors, or other equipment located in this area that is sensitive to contaminants due to material or byproduct deposition.
[0036]
While various embodiments incorporating the teachings of the invention have been shown and described in detail herein, those skilled in the art will still be able to use the teachings disclosed herein without departing from the spirit of the invention. Many other variations incorporating it can be easily invented.
[Brief description of the drawings]
FIG. 1 is a schematic cross-sectional view of a processing chamber incorporating a heat shield body of the present invention.
2 shows an exploded perspective view of the heat shield body of FIG. 1. FIG.
FIG. 3 shows a simplified exploded view of a cryopump connected to the processing chamber of FIG.

Claims (16)

An apparatus for shielding a pump apparatus from a processing chamber of a semiconductor wafer processing apparatus,
A shield,
A thermally conductive support member attached to the shield, the support member extending vertically away from the shield; and
A wherein a mounting portion of the annular mounted to the support member at the central portion, it has a fluid passage circumferential shape arranged therein, and said mounting portion,
A device characterized by comprising: A cross member extending radially inward from the annular mounting portion and coupled to the support member;
The apparatus of claim 1, further comprising: The apparatus according to claim 2 , wherein the cross member , the shield, the attachment portion, and the support member are made of copper. The apparatus of claim 1, wherein the shield has a heat reflective finish and the shield is metal plated with a material selected from the group consisting of nickel, gold and silver . The mounting portion further includes
A first sealing surface disposed on a first surface of the mounting portion;
A second sealing surface disposed on the second surface of the mounting portion;
The apparatus of claim 1, further comprising: the first and second sealing surfaces disposed inside the fluid path. The apparatus of claim 5 , wherein the first and second sealing surfaces are stainless steel, and each sealing surface further comprises a knife edge. The circumferential fluid path is:
A groove disposed on the surface of the mounting portion;
A plug disposed in the groove and flush with the surface;
Further comprising an apparatus according to claim 1. The apparatus of claim 1, wherein the processing chamber further comprises an entrance, an attachment portion is affixed to the entrance, and the shield is disposed near the entrance. The apparatus according to claim 8 , further comprising a cryopump passing through the inlet / outlet and communicating with the chamber. An apparatus for shielding a pump device from a processing chamber of a semiconductor wafer processing system,
A shield disposed within the processing chamber ;
A thermally conductive support member attached to the shield, the support member extending vertically away from the shield; and
Disposed outside of the connected said processing chamber to said shield, and a mounting portion having an internal flow path of the sealing surfaces and circumferential shape,
And the sealing surface is disposed inside the flow path. A cross member connected to the mounting portion;
A support rod coupled to the shield;
The apparatus of claim 10 , further comprising: The apparatus of claim 10 , wherein the shield is made of copper. The apparatus of claim 10 , wherein the shield has a heat reflective finish, and the shield is metal plated with a material selected from the group consisting of nickel, gold, and silver . The apparatus of claim 10 , wherein the processing chamber further comprises an entrance, an attachment portion is affixed to the entrance, and the shield is disposed near the entrance. The apparatus of claim 10 , further comprising a cryopump in communication with the chamber through the inlet / outlet. An apparatus for shielding an apparatus from a processing chamber in a semiconductor wafer processing system,
A chamber having an entrance and exit;
A cryopump coupled to the doorway;
A platform disposed within the chamber;
A heat reflecting shield disposed in the chamber between the platform and the doorway;
An attachment portion disposed between the inlet / outlet and the cryopump, the attachment portion being connected to the shield and having a fluid path outside the processing chamber disposed outside a sealing surface of the attachment portion. When,
A device characterized by comprising:

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